The present invention relates to a method for forming images using photosensitive microcapsules and, more particularly, it relates to a method in which microcapsules containing a photosensitive internal phase are deposited, as a free flowing powder, onto a support where they are image-wise exposed and ruptured. The method of the present invention obviates the need for an imaging sheet and, in accordance with certain embodiments, provides for plain paper copying.
U.S. Pat. Nos. 4,399,209 and 4,440,846 to The Mead Corporation describe transfer and self-contained imaging systems in which an imaging sheet comprising a support carrying a layer of photosensitive microcapsules and an associated color-forming agent is image-wise exposed to actinic radiation and subjected to a uniform rupturing force, such as pressure, in the presence of a developer material. The microcapsules rupture and image-wise release the internal phase, and the color-forming agent thereupon image-wise reacts with the developer material and produces an image. U.S. Pat. No. 4,399,209 describes a transfer system in which the photosensitive microcapsules and the developer material are provided on separate supports which must be combined in the imaging apparatus to form the image. U.S. Pat. No. 4,440,846 describes a self-contained imaging sheet in which the photosensitive microcapsules and developer are carried on the surface of a single sheet.
The present invention relates to a method for forming images which obviates the need for the pre-coated imaging sheets described in the aforementioned patents. The present invention is characterized in that photosensitive microcapsules are uniformly coated on a support as a free-flowing powder in the imaging apparatus.